In recent years, increased awareness of the air and water pollution problems caused by leaking gasoline or other polluting elements has focused attention on ways to detect and prevent such leaking. For example, most service stations now provide vapor recovery systems to recover the gasoline vapors or fumes liberated during the filling of an automobile fuel tank. These vapors or fumes are displaced from the tank by the inflowing gasoline. Such systems are disclosed in U.S. Pat. No. 3,756,291 and U.S. Pat. No. 3,815,327. Systems have also been developed to detect and prevent leaks from underground storage tanks and their associated lines to prevent possible ground water contamination. One such system is disclosed in U.S. Pat. No. 4,161,957.
However, efforts at preventing pollution to date have ignored a major source of possible air and water pollution in service stations. The gasoline pumps or dispensers in a service station undergo routine maintenance on a regular basis. For example, the filters in a dispenser are typically changed once a month. When the maintenance worker removes an old filter, the gasoline present in the dispenser downstream of the filter drains onto the ground beneath the dispenser. This can amount to three to five gallons of gasoline. When one considers that this amount drains from each of the dispensers in a service station on a monthly basis, it is clear that the potential pollution problem is significant.
Gasoline drainage can also occur when less frequent types of repair work, such as changing the meters, are performed on gasoline dispensers. When meters are changed, it is also typical for the maintenance worker to run some gasoline through the dispenser to ensure that the dispenser is working properly. Although the worker should run this gasoline into a container, it is common for workers to run it onto the ground at the base of a dispenser when a container is not readily available. Therefore, gasoline drainage due to this type of repair work can also pose a significant pollution problem even though it occurs on an irregular basis.
Gasoline dispensers are fitted with a shear or impact valve at the point where the dispenser is mounted on the ground. This valve automatically shuts off the supply of gasoline to the dispenser when the dispenser is damaged by a vehicle. This prevents any further gasoline from leaking out of the damaged dispenser. However, the gasoline in the dispenser downstream of the impact valve will still drain onto the ground. Also, dispensers can develop slow leaks at gaskets or other points despite regular maintenance. Such slow leaks allow a steady trickle of gasoline to drain onto the ground.
The gasoline draining from a dispenser and spilling onto the ground creates an obvious air pollution problem through evaporation of the gasoline. The potential for ground water contamination also exists from the gasoline seeping into the ground. In addition to pollution problems, the spilling gasoline creates a fire hazard. A fire at a service station can be an especially dangerous event. Therefore, fire hazards should be minimized, if not eliminated. Furthermore, the spilling gasoline represents an economic loss to service station owners.
Accordingly, a need exists for an apparatus and a method for preventing the gasoline draining from gasoline dispensers from polluting the air or water. Such apparatus and method should also recover this gasoline and return it to storage so that it will not pose a fire hazard and so that gasoline losses will be reduced. It would also be preferable for the apparatus involved to be easy to install in existing service stations and compatible with existing equipment. Additionally, the method should preferably be adaptable to work with other potential sources of leaking gasoline, such as the submersible pumps in a service station.